1. Field of the Invention
The present invention generally relates to an apparatus for evacuating and/or gas-purging a flexible bag and thereafter sealing the bag. More particularly, the present invention concerns apparatus for evacuating and/or gas-purging a bag and sealing the mouth of the bag while the exterior of the bag is exposed to ambient atmospheric conditions.
2. Description of the Prior Art
Products are often packaged in flexible bags made of gas-tight flexible thermoplastic material which is seamed in a gas-tight manner and which has a mouth that is hermetically sealable. Usually, the panels forming the mouth have at least inner surfaces formed of a heat-sealable material so that a target area across the bag mouth may be heated by die units to form a hermetical seal thereat. A wide variety of laminated web material is now available for making flexible bags, with a popular construction for vacuum-packaging being aluminum foil having a layer of polyethylene plastic on the inside surface of the foil.
An apparatus for vacuum-sealing thermoplastic pouches is illustrated in U.S. Pat. No. 2,672,268 to Bower, wherein a vacuum nozzle is inserted along a horizontal plane into the mouth of a bag and a pair of confronting resilient strips are thereafter forced toward each other above and below the nozzle to force the panels forming the bag mouth against the nozzle. While the bag is in this condition, vacuum is applied through the nozzle to collapse the bag. With the bag so collapsed and the nozzle remaining inserted, the bag mouth is sealed by die units which are operated separately from the resilient strips and which are pressed against the bag at an area between the open end where the nozzle is inserted and the closed opposite end of the bag.
U.S. Pat. No. 2,559,368 to Pancratz discloses a vacuum-sealing apparatus which includes a nozzle for applying a vacuum to a bag; a pair of opposing, conjointly operable, resilient strips, and an elongate sealing die member which is forced against a resilient anvil to seal the mouth of the bag below the nozzle. In the operation of this apparatus, a bag is vertically supported in a forming assembly, and the nozzle is driven downwardly into the bag. Then, one of the resilient strips is forced horizontally toward the other thereof such that they compress the bag panels against the side surfaces of the nozzle, the nozzle being narrower than the mouth of the bag so that the strips compress the panels against each other at the side of the nozzle. The Pancratz patent further discloses a pair of fingers which are inserted into the bag mouth with the nozzle and which are forced away from each other against the side margins of the mouth to thus flatten the mouth of the bag prior to evacuation. The arms along with the vacuum nozzle are removed after evaculation to permit a second seal to be formed nearer the outer end of the mouth.